Orienting magnetically-orientable flakes

ABSTRACT

According to examples, a substrate may be moved through a magnetic field, in which the substrate includes a fluid carrier containing magnetically-orientable flakes. The magnetic field may influence the magnetically-orientable flakes to be respectively oriented in one of multiple orientations. In addition, during movement of the substrate through the magnetic field, radiation may be applied onto a plurality of selected portions of the fluid carrier through at least one opening in a mask to cure the fluid carrier at the plurality of selected portions and fix the magnetically-orientable flakes in the plurality of selected portions at the respective angular orientations as influenced by the magnetic field.

CLAIM FOR PRIORITY AND CROSS REFERENCE TO RELATED APPLICATION

This application is a national stage filing under 35 U.S.C. § 371 of PCTapplication number PCT/US2017/049730, having an international filingdate of Aug. 31, 2017, which claims the benefit of priority to U.S.Provisional Patent Application Ser. No. 62/382,185 filed on Aug. 31,2016 and entitled “ORIENTING MAGNETIC FLAKES,” the disclosure of whichis hereby incorporated by reference in its entirety. This applicationalso contains similar subject matter to U.S. Patent Application Ser. No.62/382,187, filed on Aug. 31, 2016 and entitled “ARTICLE WITH ANGLEDREFLECTIVE SEGMENTS,” the disclosure of which is hereby incorporated byreference in its entirety.

BACKGROUND

Optically variable devices are used in a wide variety of applications,both decorative and utilitarian. Optically variable devices can be madein a variety of ways to achieve a variety of effects. Examples ofoptically variable devices include the holograms imprinted on creditcards and authentic software documentation, color-shifting imagesprinted on banknotes, and enhanced surface appearances of items such asmotorcycle helmets and wheel covers.

Optically variable devices can be made as a film or a foil that ispressed, stamped, glued, or otherwise attached to an object, and canalso be made with optically variable pigments embedded into an organicbinder that is printed or coated onto a hard or flexible substrate. Onetype of optically variable pigment is commonly called a color-shiftingpigment because the apparent color of images appropriately printed withsuch pigments changes with a change of the angle of observation. Acommon example is the “20” printed with color-shifting pigment in thelower right-hand corner of a U.S. twenty-dollar bill, which serves as ananti-counterfeiting device.

BRIEF DESCRIPTION OF THE DRAWINGS

Features of the present disclosure are illustrated by way of example andnot limited in the following figure(s), in which like numerals indicatelike elements, in which:

FIGS. 1A-1E, respectively, schematically show several apparatuses fororienting magnetically-orientable flakes, according to examples of thepresent disclosure;

FIG. 2A shows a simplified isometric view of an apparatus for orientingmagnetically-orientable flakes, according to an example of the presentdisclosure;

FIG. 2B shows a simplified isometric view of a magnet and its magneticfield, according to an example of the present disclosure;

FIG. 2C shows a simplified top view of an apparatus for orientingmagnetically-orientable flakes, according to another example of thepresent disclosure;

FIGS. 3A-3E, respectively, show views of a region of a fluid carrier inwhich magnetically-orientable flakes have been oriented, according to anexample of the present disclosure;

FIGS. 4A-4F, respectively, show examples of masks that may beimplemented in the apparatuses depicted in any of FIGS. 1A-2B, accordingto an example of the present disclosure;

FIG. 4G illustrates an orthogonal projection of an external magneticinduction onto a plane, in which the plane is normal to the substrateand contains a velocity vector of the substrate, according to an exampleof the present disclosure;

FIGS. 4H-4Q, respectively, show masks, security elements, and articlesof value, according to examples of the present disclosure;

FIG. 5A shows a simplified top view of an apparatus for orientingmagnetically-orientable flakes, according to another example of thepresent disclosure;

FIG. 5B shows a simplified isometric view of the magnetically-orientableflakes contained in a region of the fluid carrier depicted in FIG. 5A,according to an example of the present disclosure;

FIGS. 5C-5F, respectively, show diagrams and graphs of an opticalelement at different tilt angles, according to examples of the presentdisclosure;

FIG. 6A shows a simplified top view of an apparatus for orientingmagnetically-orientable flakes, according to another example of thepresent disclosure;

FIG. 6B shows a simplified isometric view of the magnetically-orientableflakes contained in a region of the fluid carrier depicted in FIG. 6A,according to an example of the present disclosure;

FIGS. 6C-6E, respectively, show diagrams and graphs of an opticalelement at different tilt angles, according to examples of the presentdisclosure; and

FIGS. 7-10, respectively, depict flow diagrams of methods for orientingmagnetically-orientable flakes, according to examples of the presentdisclosure.

DETAILED DESCRIPTION

For simplicity and illustrative purposes, the present disclosure isdescribed by referring mainly to an example thereof. In the followingdescription, numerous specific details are set forth in order to providea thorough understanding of the present disclosure. It will be readilyapparent however, that the present disclosure may be practiced withoutlimitation to these specific details. In other instances, some methodsand structures have not been described in detail so as not tounnecessarily obscure the present disclosure. As used herein, the terms“a” and “an” are intended to denote at least one of a particularelement, the term “includes” means includes but not limited to, the term“including” means including but not limited to, and the term “based on”means based at least in part on. As used herein, the terms“substantially,” “approximately,” and “about” indicate a range of valueswithin +/−5% of a stated value.

It should be noted that the elements depicted in the accompanyingfigures may include additional components and that some of thecomponents described in those figures may be removed and/or modifiedwithout departing from scopes of the present disclosure. Further, theelements depicted in the figures may not be drawn to scale and thus, theelements may have sizes and/or configurations that differ from thoseshown in the figures.

Disclosed herein are apparatuses and methods for orientingmagnetically-orientable flakes in a fluid carrier. Particularly, theapparatuses and methods disclosed herein may cause themagnetically-orientable flakes dispersed in the fluid carrier to beoriented in manners that may cause a kinematic optical effect to beobtained, e.g., a band or multiple bands of light reflected from themagnetically-orientable flakes move in directions that are perpendicularto the direction in which an optical element containing the fluidcarrier is tilted. In one regard, the magnetically-orientable flakes maybe oriented in this manner by subjecting the magnetically-orientableflakes to a magnetic field in which one or more magnetic field linesextend co-linearly with the direction in which a substrate upon whichthe fluid carrier is fed. In addition, the magnetically-orientableflakes may be fixed in desired orientations through use of a maskcontaining at least one opening, in which the mask and the at least oneopening may be strategically positioned with respect to the magneticfield to cause the magnetically-orientable flakes to be fixed at adesired dihedral angle with respect to the substrate by a radiationsource when the magnetically-orientable flakes are aligned with magneticfield lines that penetrate the substrate. Moreover, multiple layers offluid carriers having magnetically-orientable flakes may be provided andcured to create images having various optical effects.

The at least one opening of the mask disclosed herein may be any shape,size, or have any orientation. In some examples, the at least oneopening may be surrounded on all sides by the mask (e.g., openings 124of the mask shown in FIG. 2A). In other examples, the at least oneopening may have at least one open side (e.g., openings 402 of FIGS. 4A,4B, and 4D). In some examples, the at least one opening may have one ormore straight sides. Additionally or alternatively, the at least oneopening may have one or more curved sides.

The apparatuses and methods disclosed herein may also cause themagnetically-orientable flakes to be fixed while the substrate iscontinuously fed through the magnetic field. In this regard, theapparatuses and methods disclosed herein may be implemented to print andorient the magnetically-orientable flakes in a high-speed manner.Moreover, the apparatuses and methods disclosed herein may beimplemented to generate highly noticeable movement of light bands acrossoptical elements. The optical elements may be provided, for instance, onfinancial documents, such as banknotes, currency, stock certificates,etc., or other products such as software documentation, security seals,and similar objects as authentication and/or anti-counterfeitingdevices.

A dispersion of magnetically-orientable flakes in a fluid carrier asdiscussed herein may alternatively be described as a dispersion ofmagnetically-orientable flakes or magnetizable flakes in a liquidcoating, in wet ink (whether water-borne or solvent-borne, liquid ink,paste-like ink, or the like), in uncured paint (whether water-borne orsolvent-borne), in an uncured organic binder, in an uncured organiccarrier, in an uncured organic vehicle, etc.

It should be understood that the phenomenon of changing the position andalignment of one or more magnetically-orientable flakes throughapplication of a magnetic field whose source is external to the same oneor more magnetically-orientable flakes may be described in a number ofways. The present disclosure describes alignment/orientation ofmagnetically-orientable flakes in the direction of the magnetic field.Alignment/orientation of magnetically-orientable flakes may additionallyor alternatively be described in the direction of the magnetic field(the direction of a magnetic field may be defined as being tangent tothe field line at any point in space). In other examples,alignment/orientation of magnetically-orientable flakes may be describedby an external magnetic vector force.

FIG. 1A shows a schematic diagram of an apparatus 100 for orientingmagnetically-orientable flakes, according to an example of the presentdisclosure. As shown, the apparatus 100 may include a magnet 102 havinga first pole 104 and a second pole 106. The first pole 104 may have afirst polarity and the second pole 106 may have a second, oppositepolarity. For instance, the first pole 104 may be the south pole of themagnet 102 and the second pole 106 may be the north pole of the magnet102. In other examples, the first pole 104 may be the north pole and thesecond pole 106 may be the south pole. As discussed in greater detailherein below, the opposite poles of the magnet 102 may apply a magneticfield having magnetic field lines emanating from the magnet 102.Magnetic vector forces, which may also be termed “magnetic induction,”may be defined as forces that may be applied by the magnetic field invarious directions that emanate from the magnet 102. For example, one ofthe poles of the magnet 102 may face the bottom surface of thesubstrate, e.g., the surface of the substrate opposite the surfacecontaining the fluid carrier.

The apparatus 100 is also depicted as including a feeding mechanism 110in the form of a pair of rollers arranged to feed a substrate 116 in afeed direction 114. Although the substrate 116 has been depicted asbeing directly fed by the rollers, the substrate 116 may instead besupported on a support (not shown). Other kinds of feeding mechanismsare possible within a scope of the apparatus 100. The support, ifemployed, may be a belt, a platform, one or more rows of grippers, aframe, or the like, and may support the substrate 116 such that thesubstrate 116 may be moved in the feed direction 114 along with thesupport. In various examples, the apparatus 100 may include additionalfeeding mechanisms (not shown) provided upstream and/or downstream ofthe feeding mechanism 110.

The substrate 116 may be formed of paper, plastic film, laminate, cardstock, or the like. In a particular example, the substrate 116 is abanknote that may be cut into currency. The substrate 116 may also be ina continuous roll, or a sequence of substrate sheets, or have anydiscrete or continuous shape. In addition, at least a portion of anupper surface of the substrate 116 may be coated with a fluid carrier118 in which magnetically-orientable particles or flakes are dispersed.The fluid carrier 118 may also be termed an ink, a wet ink, a coating, afluid coating, or the like. The fluid carrier 118 may be applied througha printing technique such as gravure, ink-jet printing, flexographic,Intaglio, silk screen printing, painting, etc. The fluid carrier 118 maybe in the form of ink or paint and may remain in a fluid form for atleast a predetermined length of time or until a sufficient amount ofenergy is applied onto the fluid carrier 118. For instance, the fluidcarrier 118 may be a liquid or a paste-like carrier and may be curablethrough receipt of energy in the form of ultra-violet (UV) light,electron beam, heat, laser, etc. By way of particular example, the fluidcarrier 118 may be a photopolymer, a solvent-based carrier, awater-based carrier, or the like. In addition, the fluid carrier 118 maybe transparent, either clear, colorless, or tinted.

According to examples, the fluid carrier 118 with themagnetically-orientable flakes may be applied onto the substrate 116immediately prior to the substrate 116 being fed over the magnet 102such that the fluid carrier 118 remains in a fluid state as the fluidcarrier 118 is moved over the magnet 102. In this example, the feedingmechanism 110 or another mechanism (not shown), such as a printingmechanism, of the apparatus 100 may apply the fluid carrier 118 with themagnetically-orientable flakes onto the substrate 116 as the substrate116 is fed in the feed direction 114. The magnetically-orientable flakesmay be mixed into the fluid carrier 118 prior to or after the fluidcarrier 118 has been applied onto the substrate 116. According toexamples, the magnetically-orientable flakes are non-spherical andplanar flakes, e.g., pigment flakes that may be aligned using a magneticfield, and may be reflective and/or may be color shifting, e.g., themagnetically-orientable flakes may appear to have one color at oneobservation angle and another color at another observation angle. Themagnetically-orientable flakes may or may not retain remnantmagnetization. By way of example, a magnetically-orientable flake may beanywhere from about 1 to about 500 micrometers across and anywhere fromabout 0.1 to about 100 micrometers thick. In addition, themagnetically-orientable flakes may include a metallic layer, such as athin film of aluminum, gold, nickel, platinum, metal alloy, etc., or maybe a metal flake, such as a nickel, iron, or alloy flake. In addition orin other examples, the magnetically-orientable flakes may be coated witha tinted layer, or may include an optical interference structure, suchas an absorber-spacer-reflector Fabry-Perot type structure.

The magnetically-orientable flakes viewed normal to the plane of themagnetically-orientable flakes may appear bright, whilemagnetically-orientable flakes viewed along the edge of the plane mayappear dark. For example, light from an illumination source (not shown)may be reflected off the magnetically-orientable flakes to an observerwhen the magnetically-orientable flakes are in a position normal to theobserver. However, if the magnetically-orientable flakes are tilted withrespect to the plane normal to the observer, the magnetically-orientableflakes may be viewed on edge and may thus appear dark. Similarly, if themagnetically-orientable flakes are color-shifting, themagnetically-orientable flakes may appear to be one color when viewedalong the normal plane and another color or darker when viewed along atilted plane. Although particular reference is made herein tomagnetically-orientable flakes being caused to be aligned with thedirection of the magnetic field of at least one magnet, it should beunderstood that in instances, less than all of themagnetically-orientable flakes may become aligned with the direction ofthe magnetic field while still resulting in desired optical effects.

According to examples, the substrate 116 may be moved through themagnetic field of the magnet 102 before the fluid carrier 118 sets ordries to enable the magnetically-orientable flakes to become oriented inthe direction of the magnetic field. That is, the feeding mechanism 110may feed the substrate 116 along the feed direction 114 such that themagnetically-orientable flakes in the fluid carrier 118 are fed throughthe magnetic field applied by the first pole 104 and the second pole 106of the magnet 102. The magnetic field may be depicted as having lines ofmagnetic field (flux density) emanating from the poles of the magnet.Alternatively, as discussed in greater detail herein below, the magneticfield may be described as being composed of vector forces and themagnetically-orientable flakes may become closely aligned with thevector forces. In addition, as the vector forces are not uniform acrossthe magnet 102, the orientations of the magnetically-orientable flakesmay vary depending upon the locations of the magnetically-orientableflakes with respect to the first pole 104 and the second pole 106. Assuch, the orientations of the magnetically-orientable flakes may changeas the substrate 116 is fed through the magnetic field applied by thefirst pole 104 and the second pole 106. In other words, the dihedralangle of magnetically-orientable flakes may change with respect to aplane of the substrate 116. A dihedral angle may be defined as the anglebetween two planes in a third plane which cuts the line of intersectionat right angles.

As also shown in FIG. 1A, the apparatus 100 may include a radiationsource 120 (or an array of radiation sources 120), which may applyradiation onto the fluid carrier 118 to cure or otherwise solidify thefluid carrier 118 as the substrate 116 is fed in the feed direction 114.The radiation source 120 may apply radiation in the form of ultra-violet(UV) light, electron beam, heat, laser, or the like. A mask 122 havingat least one opening 124 is also depicted as being positioned betweenthe radiation source 120 and the fluid carrier 118 to control whichportion or portions of the fluid carrier 118 receives radiation from theradiation source 120 as the substrate 116 passes by the radiation source120. The locations on which radiation is incident to the substrate 116through the at least one opening may be considered a radiationfootprint. The mask 122 may have a thickness in the range of betweenabout 0.25 mm to 2.5 mm (0.01″ to about 0.1″). According to examples,the at least one opening 124 is strategically positioned with respect tothe magnet 102 and the radiation source 126 to cause themagnetically-orientable flakes to be at least partially fixed atpredetermined orientations while preventing othermagnetically-orientable flakes from being at least partially fixed atother orientations. As discussed in greater detail herein below, theopening or openings 124 may be positioned to at least partially fix themagnetically-orientable flakes to be in a helical or bi-helicalarrangement with respect to each other along a direction that isperpendicular (or equivalently, orthogonal or transverse) to the feeddirection 114 and substantially lying within the plane of the substrate116.

Further shown in FIG. 1A is a second radiation source 126, which mayalso apply energy onto the fluid carrier 118 in the form of ultra-violet(UV) light, electron beam, heat, or the like. The second radiationsource 126 may apply the same type of energy or a different type ofenergy as compared with the radiation source 120. In any regard, thesecond radiation source 126 may be optional and, if present, may beimplemented to further solidify the fluid carrier 118.

Turning now to FIG. 1B, there is shown a schematic diagram of anapparatus 100 for orienting magnetically-orientable flakes according toanother example of the present disclosure. The apparatus 100 depicted inFIG. 1B includes many of the same features as those described above withrespect to FIG. 1A and thus, those common features will not be describedin detail with respect to FIG. 1B. However, the apparatus 100 depictedin FIG. 1B differs from the apparatus 100 depicted in FIG. 1A in thatthe apparatus 100 includes a second magnet 103 positioned in sequencewith the first magnet 102 along the feed direction 114. In addition, thesecond magnet 103 is depicted as being rotated with respect to the firstmagnet 102 such that the second pole 106 is positioned closer to thesubstrate 116 than the first pole 104 of the second magnet 103. In thisregard, opposite poles of the magnets 102 and 103 are closer to thesubstrate 116. As such, the magnets 102 and 103 may generate a similarmagnetic field to the magnetic field generated by the single magnet 102depicted in FIG. 1A.

In other examples, the apparatus 100 may include an additional oradditional magnets to form a magnetic field that results in themagnetically-orientable flakes being aligned in desired orientations.

The apparatus 100 may be designed so that as the substrate 116 moves thefluid carrier 118 to positions near a magnet 102 or magnets 102/103, amagnetically-orientable flake in the fluid carrier 118 near themagnet(s) 102/103 will experience a torque according to the localmagnetic induction experienced by that magnetically-orientable flake. Ifthe torque is sufficiently strong, the magnetically-orientable flake inuncured ink will rotate about an axis parallel to the substrate 116motion until the magnetically-orientable flake is substantially alignedwith the local magnetic induction. The torque experienced by amagnetically-orientable flake depends upon the local magnetic inductionat that magnetically-orientable flake, where the local magneticinduction is a vector sum of all external magnetic induction. Inpractice, unwanted sources of magnetism may be sufficiently isolatedfrom where curing takes place so that their contribution to the totallocal magnetic induction may be neglected when compared to the magneticinduction provided by the magnet(s) 102/103. For example, it may beundesirable for the parasitic magnetic induction emanating from anelectric motor to interfere with the alignment ofmagnetically-orientable flakes just before curing takes place.Accordingly, the magnetic induction provided by the magnet(s) 102/103may be termed the external magnetic induction, it being understood thatthe external magnetic induction is the magnetic induction due to themagnet(s) 102/103, or due to one or more magnets purposefully positionedin the apparatus 100 for the purpose of tilting and orienting themagnetically-orientable flakes. The magnet(s) 102/103 may be a permanentmagnet or an electromagnet, and may include an assembly of such magnets.Accordingly, it is sufficient to refer to the external magneticinduction when describing various embodiments without necessarilyreciting a particular magnet or magnet assembly. Furthermore, often theterms “external magnetic induction” and “external magnetic inductionvector” are used interchangeably.

With reference now to FIGS. 1C-1E, there are respectively shownschematic diagrams of apparatuses 100 for orientingmagnetically-orientable flakes according to additional examples of thepresent disclosure. As shown in FIG. 10, the substrate 116 may be aflexible substrate and may be supported by a roller 130 having a radius132. The roller 130 may be formed of a non-magnetic material, forinstance, a plastic material, a rubber material, a ceramic material,etc. A fluid carrier 118 containing magnetically-orientable flakes maybe provided on an upper surface of the substrate 116 (e.g., the surfaceof the substrate substantially facing the magnets 102 and 103 and/orradiation source 120 and substantially opposite the roller 130). Theapparatus 100 depicted in FIG. 10 may include magnets 102 and 103 thatare positioned with respect to the roller 130 such that their opposingpoles 104 and 106 form a magnetic field through which portions of thesubstrate 116 are fed as the roller 130 rotates in the direction denotedby the arrow 136. The magnetic field, which may be represented by thelines 138, may include vector forces whose respective directions aresubstantially parallel to each other in the middle of the magneticfield, and a radiation source 120 may be positioned to apply energy ontothe fluid carrier 118 close to a central location between the magnets102 and 103. FIG. 10 thus shows an example in which the substrate 116instantaneously moves along the north-south cardinal direction of atleast a nearly linear magnetic field (e.g., a low degree of magneticline curvature).

Similarly to the apparatus 100 depicted in FIGS. 1A and 1B, theradiation source 120 depicted in FIG. 10 may apply radiation onto thefluid carrier 118 to cause at least partial solidification of the fluidcarrier 118. In addition, a mask 122 including at least one opening 124(not shown) may be positioned between the radiation source 120 and theroller 130 to selectively block application of the radiation from theradiation source 120 onto the fluid carrier 118 (e.g., create theradiation footprint) and thus control the orientations at which themagnetically-orientable flakes may be fixed within the fluid carrier118. According to examples, the mask 122 may be positioned a distance134 from a center of the roller 130 such that a difference between theradius 132 of the roller 130 and the distance 134 is a value rangingfrom about 0.05 mm to about 6.25 mm (about 0.002 inches to about 0.25inches).

FIG. 1D shows a similar arrangement to the arrangement shown in FIG. 10,except that the magnetic field generation is different. That is, insteadof the linear field generated in FIG. 10, in FIG. 1D, the generatedmagnetic field is substantially curved at a location on the substrate116 at which the radiation source 120 applies radiation. As shown, themagnet 102 may include a hole 140 through which a light guide 142 fromthe radiation source 120 may be inserted. Alternatively, however,multiple magnets may be positioned to generate the magnetic field shownin FIG. 1D. It should be noted that hole 140, light guide 142, and/ormultiple magnets may be used with any apparatus and/or arrangement,including but not limited to the apparatuses of FIGS. 1A-C and 1E.

FIG. 1E shows a similar arrangement to the arrangement shown in FIG. 10,except that the magnet 102 is positioned within the roller 130. That is,the roller 130 depicted in FIG. 1E may be a hollow cylinder and themagnet 102 may be positioned inside of the roller 130. In addition, themagnet 102 may be held in a stationary manner such that the magnet 102does not move or rotate as the roller 130 is rotated. In other words,the magnet 102 may be maintained in a fixed spatial relationship withrespect to the radiation source 120. In addition, the magnetic fieldthrough which portions of the substrate 116 may be moved may differ fromthe magnetic fields shown in FIGS. 10 and 1D.

In each of the examples discussed above, the substrate 116 has beendescribed as being moved by a cylindrical roller 130. In other examples,however, instead of a roller 130, the apparatus 100 may include a curvedsurface on which the substrate 116 may be in sliding contact. Inaddition, or alternatively, the substrate 116 may have a curved shapethat may be supported on a curved surface, such as a roller 130, or maybe supported in other manners. By way of example, the substrate 116 mayhave a curved shape that may be supported by a parabolic curved surfacein sliding contact.

According to examples, any of the apparatuses 100 depicted in FIGS.1A-1E may include multiple stations, in which each of the multiplestations includes a respective set of magnets 102, masks 122, andradiation sources 120. In these examples, the stations may be arrangedsuch that the substrate 116 may be moved through each of the stationssequentially. In addition, each of the stations may include a respectivefluid applying mechanism to apply an additional layer of the fluidcarrier 118. As such, for instance, a surface of the substrate 116 maybe coated with a first fluid carrier 118 and the first fluid carrier 118may be exposed to a magnetic field and radiation to orient themagnetically-orientable flakes in the first fluid carrier 118. After thefirst fluid carrier 118 has been cured, a second fluid carrier 118 maybe applied onto the cured first fluid carrier 118. The second fluidcarrier 118 may also be exposed to a magnetic field and radiation toorient the magnetically-orientable flakes in the second fluid carrier118.

The magnetically-orientable flakes in the second fluid carrier 118 maybe oriented in the same or in a different manner as themagnetically-orientable flakes in the first fluid carrier 118. That is,for instance, the magnetically-orientable flakes in the second fluidcarrier 118 may have the same configuration as themagnetically-orientable flakes in the first fluid carrier 118 ormagnetically-orientable flakes in the second fluid carrier 118 may havea different configuration than the magnetically-orientable flakes in thefirst fluid carrier 118. Moreover, an additional layer or layers offluid carrier 118 may be applied and cured in additional stations. Inone regard, the multiple stations may be implemented to fabricate anarticle to include multiple coatings of fluid carriers 118.

By way of example, the first fluid carrier 118 may be a clear or dyedink or paint vehicle, mixed with reflecting or color-shifting ofdiffractive or any other platelet-like magnetic pigment of oneconcentration (e.g., between about 15-50 weight %). The first fluidcarrier 118 may be printed/painted on the surface of the substrate 116in any predetermined graphical pattern, exposed to the magnetic field toform a predetermined optical effect, and cured to fix themagnetically-orientable flakes in the layer of first fluid carrier 118after solidification of the first fluid carrier 118. The second fluidcarrier 118 may be of relatively lower concentration (e.g., in the rangeof between about 0.1-15 wt. %). The ink or paint vehicle for the secondfluid carrier 118 may be clear or dyed. The magnetically-orientableflakes in the second fluid carrier 118 may be the same as for the firstfluid carrier 118 or they may be different. The flake sizes for thesecond fluid carrier 118 may also be the same or different from theflake sizes for the first fluid carrier 118. Moreover, the color of theflakes for the second fluid carrier 118 may be the same or differentfrom the color of the flakes for the first fluid carrier 118. The shapeand/or intensity of the magnetic field applied to the second fluidcarrier 118 may be the same or different from the shape and/or intensityof the magnetic field applied to the first fluid carrier 118. Inaddition or in other examples, the graphical pattern for the secondfluid carrier 118 may be the same or different from the graphicalpattern for the first fluid carrier 118. In any regard, a combination ofinks or pigment colors may either enhance or depress a particular colorin the image formed from the multiple layers of fluid carriers 118.

According to examples, through application and curing of multiplecoatings of fluid carriers 118 on a substrate 116 as disclosed herein,an image may be formed of the magnetically-orientable flakes such thatmultiple distinct features within the image may appear to movesimultaneously. In addition, the movement may be relative movement whenthe image is moved or when the light source upon the image is moved. Inaddition or in other examples, multiple distinct features within theimage may appear to move, in which one is stationary while the othermoves, and vice versa, when the image is moved in different directionsor when the light source upon the image is moved in differentdirections. In particular examples, through application and curing ofmultiple coatings of fluid carriers 118 on a substrate 116 as disclosedherein, complex patterns of lines, points, arcs, and other shapes,enhanced with optically-illusive effects may be utilized in an articleprinting process to make it difficult for visually encrypted articles tobe counterfeited.

With reference now to FIG. 2A, there is shown a simplified isometricview of an apparatus 200 for orienting magnetically-orientable flakesaccording to another example of the present disclosure. The apparatus200 depicted in FIG. 2A includes many of the same features as thosedescribed above with respect to FIGS. 1A and 1B and thus, those commonfeatures will not be described in detail with respect to FIG. 2A.

In FIG. 2A, a plurality of magnetic field lines 202 generated or appliedby the magnet 102 and/or magnets 102/103 are shown. The box labeled102/103 represents either or both of the magnets 102 and 103. FIG. 2Aalso shows that undulation points 204 on the curves of the magneticfield lines 202 are located along a line 206 that extendsperpendicularly to the feed direction 114. The line 206 may beconsidered as an axis of reflectional symmetry of the magnetic fieldlines 202. As shown, the substrate 116, with the fluid carrier 118, maybe moved rectilinearly in the feed direction 114 such that the fluidcarrier 118 moves over the magnet(s) 102/103 and through the magneticfield lines 202 of the magnetic field generated by the magnet(s)102/103. In the example shown in FIG. 2A, the entire surface of thesubstrate 116 is depicted as being coated with the fluid carrier 118.However, it should be understood that smaller portions of the substrate116 may be coated with the fluid carrier 118 without departing from ascope of the present disclosure.

The substrate 116 is depicted as being moved through the magnetic fieldin a direction from the south pole to the north pole of the magnet(s)102/103. In other examples, however, the positions of the poles may bereversed. In any regard, as the substrate 116 is moved, themagnetically-orientable flakes in the fluid carrier 118 may becomeclosely aligned with the direction of the magnetic field (along themagnetic field lines 202) to which the magnetically-orientable flakesare subjected. In addition, the orientations of the individualmagnetically-orientable flakes may change as a function of time as themagnetically-orientable flakes move through and become aligned in thedirection of different lines of the magnetic field lines 202. Accordingto examples, the substrate 116 may be fed at a sufficiently slow rate toenable the magnetically-orientable flakes to become aligned with thedirection of magnetic field lines 202 and to attain desired orientationswith respect to the plane of the substrate (e.g., dihedral angles).

While the substrate 116 is being fed and the magnetically-orientableflakes have become closely aligned with the direction of some of themagnetic field lines 202, the radiation source 120 may direct radiationtoward the fluid carrier 118. However, the mask 122 positioned betweenthe radiation source 120 and the fluid carrier 118 may block theradiation from reaching the fluid carrier 118 except through theopenings 124 formed in the mask 122. The mask 122 may be separated fromthe substrate 116 by a relatively short distance, for instance, adistance that is between about 0.05 mm to about 6.25 mm (about 0.002inches to about 0.25 inches). In the example illustrated in FIGS. 2A and2B, the mask 122 is shown as having two rectangular openings 124 throughwhich radiation 208 from the radiation source 120 may be directed ontothe regions 210 and 212 of the fluid carrier 118 located beneath theopenings 124. In other examples, however, the mask 122 may include afewer or a greater number of openings 124. As discussed in greaterdetail herein, the openings 124 may have different sizes and/or shapesand may be positioned at an edge of the mask 122.

The openings 124 are depicted as being formed at offset locations on themask 122 with respect to the feed direction 114. In one regard,therefore, a different set of vector forces (shown schematically asmagnetic field lines 202) may act upon the first region 210 as comparedwith the second region 212. The magnetically-orientable flakes containedin the first region 210 may thus become aligned along the direction ofmagnetic field lines 202 that penetrate the plane of substrate in thefirst region 210 thus resulting in the magnetically-orientable flakesachieving a first dihedral angle (e.g., the angle of the flake “out” theplane of the substrate). The first dihedral angle is different ascompared to the magnetically-orientable flakes contained in the secondregion 212 that may become aligned along the direction of magnetic fieldlines 202 that penetrate the plane of the substrate 116 within thesecond region 212 and thus achieving a second dihedral angle. Thus, themagnetically-orientable flakes located in the first region 210 may havedifferent orientations (e.g., dihedral angles with respect to a plane ofthe substrate 116) as compared with the magnetically-orientable flakeslocated in the second region 212. In addition, themagnetically-orientable flakes in the first and second regions 210 and212 may at least be partially fixed through application of the radiation208 onto the regions 210 and 212. That is, the application of theradiation 208 may cause the fluid carrier 118 in the regions 210 and 212to at least partially solidify and the partial or total solidificationof the fluid carrier 118 may cause the magnetically-orientable flakes inthose regions 210 and 212 to become at least partially fixed in thedihedral angle (e.g., orientation of the flake “out” of the plane of thesubstrate) that the magnetically-orientable flakes have attained ascaused by the vector forces (shown schematically as magnetic field lines202) to which those magnetically-orientable flakes are subjected.

The portions of the fluid carrier 118 that have been at least partiallysolidified through receipt of the radiation 208 as the substrate 116 isfed in the feed direction 114 are depicted as regions 214 and 216. Thefirst region 214 may contain magnetically-orientable flakes that havebeen aligned along the direction of a first set of magnetic field lines202 and the second region 216 may contain magnetically-orientable flakesthat have been aligned along the direction of a second set of magneticfield lines 202. According to examples, the openings 124 are positionedwith respect to the magnet or magnets 102/103 such that themagnetically-orientable flakes are aligned along the direction ofsections of magnetic field lines 202 having predetermined angles.

In FIG. 2A, the substrate 116 is depicted as being moved rectilinearlyalong the north-south cardinal direction of the magnetic field appliedby the magnet(s) 102/103 and along a surface that is physically locatedbetween the magnet(s) 102/103 and the radiation source 120. Each of thecurved magnetic field lines 202 may be represented by two partsconnected at an undulation point 204 of every curve and may have aconvex curve shape. Each of the curved magnetic field lines 202 mayincline at an average angle α from the surface(s) of the magnet(s)102/103 (as shown in FIG. 2B) to one of the corresponding undulatingpoints 204 as illustrated with the corresponding black arrow 218. Thetangent of the magnetic field lines at undulation point 204 coincideswith the feed direction 114 of the substrate 116. In addition, thecurved magnetic field lines decline at an average angle β from thecorresponding undulation point 204 to the surface(s) of the magnet(s)102/103 (as shown in FIG. 2B) in the direction of the black arrow 220 inthe right portions of the magnetic field lines 202. FIG. 2B illustratesa simplified view of an exemplary magnet 102/103 and the magnetic fieldsthe magnet 102/103 produces.

Turning now to FIG. 2C, there is shown a simplified top view of anapparatus 200 for orienting magnetically-orientable flakes according toanother example of the present disclosure. The apparatus 200 depicted inFIG. 2C includes many of the same features as those described above withrespect to FIG. 2A and thus, those common features will not be describedin detail with respect to FIG. 2C. The radiation source 120 has beenomitted from FIG. 2C such that the mask 122 and the openings 124 maymore readily be visible.

As shown in FIG. 2C, the substrate 116 may be fed in the feed direction114 over a magnet(s) 102/103 such that the fluid carrier 118 may bemoved through a magnetic field applied along the north-south cardinaldirection of the magnetic field as represented by the arrow 220. Theundulation points 204 (FIG. 2A) of the applied magnetic field may becentered along the line 206, which may denote an axis of reflectionalsymmetry of the magnetic field lines 202 (FIG. 2A). The openings 124 inthe mask 122 are depicted as being positioned on opposite sides of theline 206 and in rotational symmetry with respect to a point that isadjacent to both of the openings 124.

As such, the first region 210 of the fluid carrier 118 beneath the firstopening 124 is within an inclining portion 222 of the curved magneticfield lines 202 and the second region 212 of the fluid carrier 118beneath the second opening 124 is within a declining portion 224 of thecurved magnetic field lines 202. In this regard, themagnetically-orientable flakes located in the first region 210 may havedifferent orientations than the magnetically-orientable flakes locatedin the second region 212. For instance, the magnetically-orientableflakes located in the first region 210 may have a dihedral angle α withrespect to the major plane of the substrate 116 that is in the range ofabout 0°<α<90°. In addition, the magnetically-orientable flakes locatedin the second region 212 may have a dihedral angle β with respect to themajor plane of the substrate 116 that is also in the range of about0°<β<90°. It should be noted in the example of FIG. 2C that the dihedralangle α is taken in the feed direction 114 whereas the dihedral angle βis taken in the direction opposite to the feed direction 114. Thereforethe angle represented by the dihedral angle β may alternatively bethought of as angle α when the angle taken along the feed direction isin the range of about 90°<angle<180°.

The radiation source 120 may apply radiation 208 (FIG. 2A) through theopening 124 in the mask 122, in which the applied radiation 208 maycause the fluid carrier 118 to at least begin to solidify, which mayresult in the magnetically-orientable flakes upon which the radiation208 is applied to at least partially begin to be fixed in variousorientations with respect to the major plane of the substrate 116. Inaddition, as the substrate 116 may continuously be fed in the feeddirection 114 as solidification of portions of the fluid carrier 118 isat least begun, the magnetically-orientable flakes in different portionsof the fluid carrier 118 may have different orientations as denoted bythe regions 214 and 216. Moreover, as the mask 122 may be positioned ata relatively short distance away from the substrate 116, the widths ofthe regions 214 and 216 may closely coincide with the widths of theopenings 124. However, because radiation 208 may be applied as thesubstrate 116 is moved in the feed direction 114, the lengths of theregions 214 and 216 may be much longer than the lengths of the openings124 and may depend upon the length of the substrate 116, lengths ofindividual sections of the fluid carrier 118, etc.

As also shown in FIG. 2C, the magnetically-orientable flakes located inthe portions of the fluid carrier 118 that do not receive radiation 208from the radiation source 120 may either return to the orientations thatthe magnetically orientable flakes had prior to being introduced to themagnetic field or may have orientations that may align with thedirections of the last sets of magnetic field lines that were applied tothose magnetically orientable flakes. The regions 226 and 228 of thefluid carrier 118 that did not receive radiation 208 through theopenings 124 are also depicted in FIG. 2C. As may be seen in thatfigure, the orientations of the magnetically orientable flakes containedin the regions 226 and 228 may differ from the orientations of themagnetically orientable flakes contained in the regions 214 and 216. Inaddition, the fluid carrier 118 contained in the regions 226 and 228 maynot have been solidified and may thus require the application ofadditional energy to solidify those regions 226 and 228.

In another example, the undulation points 204 (FIG. 2A) of the appliedmagnetic field are centered along the line 206—which may denote an axisof reflectional symmetry of the magnetic field lines 202 (FIG. 2A)—butthe openings 124 in the mask 122 are not positioned on opposite sides ofthe line 206 but instead are both positioned to be closer to one pole ofthe magnet than they are to the opposite pole. This positioning of theopenings 124 in the mask 122 may result in magnetically-orientableflakes achieving orientations (and dihedral angles with respect to theplane of the substrate) that are different from the example of FIG. 2C.This is due to the fact that the direction of magnetic field lines 202that penetrate the plane of substrate in the first region 210 and secondregion 212 of this example are different from the direction of magneticfield lines 202 that penetrate the plane of the substrate in the firstregion 210 and second region 212 of the example of FIG. 2C.

In another example, unlike the example shown in FIG. 2C, the openings124 may not contact line 206 (e.g., may be separated from contact line206 in the feed direction and/or opposite the feed direction). Thispositioning may result in magnetically-orientable flakes with a smallerdihedral angle α and a dihedral angle β (e.g., closer to parallel withthe plane of the substrate). In another example, unlike the exampleshown in FIG. 2A, the closest edges of a first opening 124 to a secondopening 124 may not be continuous, but rather, may be separated by adistance in the feed direction 114. This positioning may result in agreater difference between dihedral angle α and the complimentary angleto dihedral angle β (e.g., 180 degrees minus dihedral angle β).

With reference now to FIG. 3A, there is shown a simplified isometricview 300 of the magnetically-orientable flakes located in the regions214 and 216 of the fluid carrier 118 depicted in FIG. 2B. As shown, afirst set of magnetically-orientable flakes 302 located in the firstregion 214 may be oriented at a dihedral angle α with respect to themajor plane of the substrate 116 taken in the feed direction 114. Inaddition, a second set of magnetically-orientable flakes 304 located inthe second region 216 may be oriented at a dihedral angle β with respectto the major plane of the substrate 116 taken in the direction oppositeto the feed direction 114. As the magnetically-orientable flakes 302 and304 may become oriented as the substrate 116 is continuously moved inthe feed direction 114, the first set of magnetically-orientable flakes302 may have the same or similar orientations and dihedral angles asother flakes within the first set of magnetically-orientable flakes 302.Likewise, the second set of magnetically-orientable flakes 304 may havethe same or similar orientations and dihedral angles as othermagnetically-orientable flakes 304 within the second set ofmagnetically-orientable flakes 302.

When the substrate 116 is positioned as shown in FIG. 3C, and the upperright corner is rotated forth or back about a horizontal axis 306 asshown in FIG. 3C, light may be reflected from the first set ofmagnetically-orientable flakes 302 differently from the second set ofmagnetically-orientable flakes 304 depending on the position of theviewer and the light. The differences in the reflectance of the flakes302 and 304 are illustrated in comparison between FIGS. 3B and 3C. FIG.3B shows a top (near-normal) view 310 of the arrangement shown in FIG.3A and FIG. 3C shows a tilted view 320 of the arrangement shown in FIG.3A. FIG. 3B thus shows the effect of light reflecting from both thefirst set of magnetically-orientable flakes 302 and the second set ofmagnetically-orientable flakes 304. In FIG. 3B, the second set ofmagnetically-orientable flakes 304 is depicted as reflecting light backto an observer, e.g., is bright (may appear silver if themagnetically-orientable flakes are achromatic) and the first set ofmagnetically-orientable flakes 302 is depicted as not reflecting lightback to the observer, e.g., is dark (may appear black if themagnetically-orientable flakes are achromatic). FIG. 3C shows thearrangement being tilted about a horizontal axis 306 such that a toppart of the arrangement is tilted away from the observer. In FIG. 3C,tilting of the arrangement causes the first set ofmagnetically-orientable flakes 302 to reflect light back to theobserver, e.g., is bright (may appear silver if themagnetically-orientable flakes are achromatic) and the second set ofmagnetically-orientable flakes 304 is depicted as not reflecting lightback to the observer, e.g., is dark. In other examples in which themagnetically-orientable flakes belong to the family of interferencecolor-shifting pigments, the reflected hues observed of the sets ofmagnetically-orientable flakes 302, 304 may correspond to colorcharacteristics of the pigment at the angles at which themagnetically-orientable flakes are tilted in the fluid carrier 118 withreflect to the light. For example, at a first angle of observance, thefirst set of magnetically-orientable flakes 302 may reflect light backto the observer in the blue spectrum range and the second set ofmagnetically-orientable flakes 304 may reflect light back to theobserver in the green spectrum range of wavelengths. At a second angleof observance, the first set of magnetically-orientable flakes 302 mayreflect light back to the observer in the green spectrum range and thesecond set of magnetically-orientable flakes 304 may reflect light backto the observer in the blue spectrum range of wavelengths.

The shifting optical effects of the magnetically-orientable flakes 302,304 are further shown and described with respect to FIGS. 3D and 3E.FIGS. 3D and 3E, respectively, show an example of an optical element 330in various tilting states. The optical element 330 may be an opticalsecurity device, which may be provided on a banknote, stock certificate,or the like. FIG. 3D depicts the optical characteristics of the opticalelement 330 when the optical element 330 is viewed at a first angle,e.g., from a direction normal to the optical element 330. The graph 332shows that the left side of the optical element 330 appears white (e.g.,bright) and the right side of the optical element 330 appears black(e.g., dark). FIG. 3E depicts the optical characteristics of the opticalelement 330 when the optical element 330 is tilted away from an observeras noted by the arrow 334. The graph 336 shows that the left side of theoptical element 330 appears black (e.g., dark) and the right side of theoptical element 330 appears white (e.g., bright). As shown in FIGS. 3Dand 3E, the magnetically-orientable flakes are oriented such thattilting of the optical element 330 in one direction (e.g., top tobottom) results in an optical shift in the opposite direction (e.g.,left to right).

Although the optical element 330 has been depicted as having a squareshape and two opposing sides, it should be understood that the opticalelement 330 may have any shape and any number of sides. Examples inwhich the optical element 330 includes additional sides are described ingreater detail hereinbelow.

Although particular reference has been made above to the mask 122 ashaving a pair of openings 124 positioned as shown in FIGS. 2A-2C, itshould be understood that masks having other opening 124 (orequivalently cutout) configurations may be implemented in theapparatuses 100, 200. The other opening 124 configurations may result insets of magnetically-orientable flakes having different orientationswith respect to each other than the orientations depicted in FIGS.3A-3C. Examples of masks 400-430 having other opening configurationsthat may be implemented in the apparatuses 100, 200 are depicted inFIGS. 4A-4F.

By way of example, the mask 400 depicted in FIG. 4A is shown as having aplurality of openings 402 formed along an edge of the mask 400. The edgeof the mask 400 at which the openings 402 are formed may be the edge ofthe mask 400 that is to be positioned to abut a line 206 that representsthe axis of reflectional symmetry of the magnetic field lines 202 (FIGS.2A-2C) along the feed direction 114 of the substrate 116. The mask 410depicted in FIG. 4B is shown as having an opening 402 that is elongatedalong the feed direction 114 and in which the opening 402 is formed atan edge of the mask 410 that is positioned to abut the line 206 thatrepresents the axis of reflectional symmetry of the magnetic field lines202.

The mask 420 depicted in FIG. 4C is shown as having a plurality ofopenings 402 positioned on opposite sides of the line 206 thatrepresents the axis of reflectional symmetry of the magnetic field lines202 with respect to the feed direction 114. Adjacent ones of theplurality of openings 402 are also depicted as being offset with respectto each other along the direction that is perpendicular to the feeddirection 114. The mask 430 depicted in FIG. 4D is shown as having aplurality of openings 402 on one side of the line 206 that representsthe axis of reflectional symmetry of the vector forces 202 and a largeropening 402 on the opposite side of the line 206. In addition, thelarger opening 402 is depicted as extending beyond the rightmost smalleropening 402 along the direction perpendicular to the feed direction 114.

In still another example, the plurality of openings 402 mayalternatively be positioned on the same side of the line 206 as opposedto some being positioned on one side, and the remainder positioned onthe opposite side of the line 206. For example, each of the openings 402may be positioned in the feed direction 114 of line 206. Alternatively,each of openings 402 may be positioned opposite the feed direction 114of line 206.

A mask 122 may provide a radiation footprint from the radiation source120 on the deposited fluid carrier. For a radiation source illuminatinga mask 122, the opening 124 in the mask 122 defines the radiationfootprint whereby radiation from the radiation source 120 is emittedonto the substrate. In some examples, curing begins as the substrate 116moves deposited ink into the radiation footprint. The mask 122, and forthat matter, the radiation footprint defined by the mask 122 and theradiation source 120, may be viewed as having a leading edge. Theleading edge may be defined as the locus of positions where theradiation is first emitted on the fluid carrier 118.

FIGS. 4E and 4F provide two examples in which a mask defines a leadingedge of a radiation footprint. For the mask 440, the leading edge 442 isillustrated to the right of mask 440. The extent of the leading edge 442in the feed direction 114 is indicated by the variable x. The mask 450illustrates another example, in which the extent of the leading edge 452in the direction of feed direction 114 is again represented by thevariable x. As seen in FIGS. 4E and 4F, a leading edge may bediscontinuous. In other examples, the leading edge (e.g., the leadingedge of the mask in FIG. 6A) may include a continuous portion that hasan extent along feed direction 114. The value of the extent of a leadingedge may be between 0.5 mm and 30 mm, or 1 mm to 20 mm. In someexamples, the extent may be less than 2 mm or less than 1 mm. In otherexamples, the extent may be greater than 10 mm or greater than 20 mm.

In the some examples, the external magnetic induction varies indirection along all or at least a portion of a leading edge. FIG. 4Gillustrates the relative variation in direction of the external magneticinduction at two points labeled 1 and 2 in a leading edge of the mask460, where {right arrow over (B)}(1) and {right arrow over (B)}(2)denote, respectively, the external magnetic induction at positions 1 and2. The feed direction is represented by the arrow 114. The planes 462and 464 are normal to the substrate 116 and contain the substratevelocity vector. The orthogonal projection of the external magneticinduction {right arrow over (B)}(1) onto the plane 462 is indicated bythe vector labeled 466, and the orthogonal projection of the externalmagnetic induction {right arrow over (B)}(2) onto the plane 464 isindicated by the vector labeled 468. The relative direction of theorthogonal projection of the external magnetic induction varies amongthe positions 1 and 2. For some embodiments, this variation in directionmay only be on the order of a few degrees or less, but may be greaterfor other embodiments. For the particular example of FIG. 4G, the polarangle of the orthogonal projection of the external magnetic induction atposition 2 is larger than that at position 1, where the polar angle istaken with respect to the normal to the plane of the substrate 116.

Note that with respect to an orthogonal projection, the planes 462 and464 are equivalent. That is the planes 462 and 464 may belong to anequivalence class for the purpose of defining an orthogonal projection.Accordingly, when describing an orthogonal projection, only one planenormal to the substrate and containing the substrate velocity vector mayneed to be considered. The coordinate system 470 may be useful whendescribing the orthogonal projection. The x-axis and y-axis for thecoordinate system 470 lie in the plane of the substrate for those casesin which the substrate is planar in the vicinity of the leading edge ofthe mask 460, or equivalently, the x-y plane lies in the plane of themagnetic ink (alternately referred to as magnetically-orientable flakedispersed in a fluid carrier) or radiation footprint, where the x-axisis parallel to the direction of substrate motion. The z-axis is normalto the plane of the substrate (or magnetic ink or radiation footprint).

The planes 462 and 464 are parallel to the x-z plane of the coordinatesystem 470, and when considering orthogonal projections, the x-z planeand the planes 464 and 466 belong to the same equivalence class becauseorthogonal projections of a vector onto these planes yield the sameresults. The planes 462 and 464 are translations of the x-z plane in thedirection of the y-axis.

In instances in which the substrate is curved about a roller, thecoordinate system 470 may be generalized to a coordinate system in whichthe y-axis is parallel to and/or coincident with the roller axis. Thex-axis may be directed along a substrate velocity vector, but this isnot necessary because rotating the z-axis of the coordinate system 470about the y-axis to yield a rotated coordinate system does not changethe orthogonal projection. That is, the orthogonal projection of avector onto the x-z plane yields the same result as an orthogonalprojection of the vector onto the x-z′ plane for a rotated coordinatesystem where the rotation is about the y-axis. Accordingly, whendescribing the orthogonal projection of the external magnetic inductiononto a plane, the plane may be taken as normal to the substrate andcontaining the substrate velocity vector, or for the case in which thesubstrate is curved about a roller, the plane may be taken as normal tothe axis of the roller.

For the case in which the substrate is curved about a roller, it is alsosufficient to describe a plane for orthogonal projections as a planenormal to the substrate and containing a velocity vector of thesubstrate. Here, “normal” at a position (set of coordinates) where thesubstrate is wrapped around a roller refers to the local normal at thatposition, which may be taken as a vector containing that position andnormal to the roller axis. Regarding the velocity vector, although thevelocity vector of the substrate at some position when wrapped around aroller is not constant in direction, but is a function of position, itnevertheless lies in a plane normal to the axis of the roller. Planesnormal to the roller axis are an equivalence class for the purpose oforthogonal projections, so that the orthogonal projection of theexternal magnetic induction onto a plane normal to the substrate andcontaining a velocity vector of the substrate may also be taken as theorthogonal projection onto a plane normal to the roller axis.

Accordingly, whether that part of the substrate subject to the radiationfootprint is planar or wrapped about a roller, for the purpose ofdescribing the orthogonal projection of the external magnetic inductionalong the leading edge of the radiation footprint, it is sufficient totake the orthogonal projection onto a plane normal to the substrate andcontaining a velocity vector of the substrate.

Turning now to FIGS. 4H and 4I, there are respectively shown perspectiveviews of a mask 480 and an article 482 that may be implemented to orientmagnetically-orientable flakes such that the orientedmagnetically-orientable flakes may cause an ortho-parallactic motion ofa synthetic image across the substrate 482 as the substrate 482 isrotated about an axis. An ortho-parallactic motion or effect may bedescribed whereby tilting the upper edge of the article 482 away from ortowards an observer, he or she may perceive a bright shape of reflectedlight moving from left to right or right to left. As another example, bytilting the left edge away from or towards an observer, he or she mayperceive a bright shape of reflected light moving from top to bottom orbottom to top. In some examples, if and how the effect is perceived maydepend upon how the magnetically-orientable flakes are placed on orwithin the article 482, whether the upper edge is tilted away from ortowards the observer, and/or the position, strength, and/or distance ofthe light source. Alternatively, an ortho-parallactic optical motion oreffect may be described whereby there exists an axis of rotation (theaxis lying in the article) such that an observer rotating the articleabout the axis, depending on the light source, observes a reflectiveshape or image moving along the axis of rotation. An ortho-parallacticoptical motion or effect may further be described as an optical effectin which an optical feature such as a shape that appears brighter ordarker than other sections of the article appears to move across thearticle in a direction that is orthogonal to the tilting direction ofthe article. Thus, for instance, when the article is tilted about ahorizontal axis, the optical feature may appear to move in alongitudinal direction.

As shown in FIG. 4H, the article 482 may include a substrate 116 and afluid carrier 118, both of which are described above. In addition, themask 480 may include a stepped configuration such that as the article482 is moved in the direction denoted by the arrow 486, themagnetically-orientable flakes 484 in different locations across thewidth of the article 482 may be locked into multiple rotationalpositions with respect to each other. The rotational positions of themagnetically-orientable flakes 484 are depicted as having differentshadings in FIG. 4H and are depicted as having different angles ofrotation in FIG. 4I. As discussed above, the magnetically-orientableflakes 484 may be rotated into the angles depicted in FIG. 4I throughapplication of a magnetic field onto the magnetically-orientable flakes484 and through application of radiation to at least partially solidifythe fluid carrier 118 in a configuration consistent with the mask 480.In addition, FIG. 4J depicts an example in which themagnetically-orientable flakes 484 are oriented at angles that rangebetween −40° and 40°.

The optical effect of the article 482 may be a bright band that movessideways when the article 482 is tilted forth and back with respect to alight source. The kinematic light (or bright) band may be made to bemore attractive or appealing by creating the article 482 to generate asynthetic kinematic image, which moves transversely within the marginsof the article 482 with respect to the direction in which the article482 is moved. By way of example, the synthetic kinematic image may be acontour of an object, a symbol, a numeral, a letter, combinationsthereof, etc.

The article 482 may be provided on an article of value 488 as shown inFIG. 4K as a security element. The article of value 488 is depicted as abanknote and the article 482 has been depicted as a rectangular-shapedsecurity element 702. It should be noted that the article or securityelement 482 is merely exemplary and is not limited to rectangular-shapedor use with bank notes or as a security element. For example, thesecurity element 482 may be used on any article, including but notlimited to, labels, packaging, advertisements, etc., and may have anyshape. The different shades depicted in the security element 482 mayrepresent light being reflected at different angles and thus, dependingupon the tilt angle of the article of value 488, a different section ofthe security element 482 may be viewed as a synthetic image. Inaddition, through rotation of the article of value 488, the syntheticimage may be viewed as a synthetic kinematic image as the syntheticimage may appear to move.

The synthetic kinematic image is further described with respect to FIGS.4L and 4M, which depict the article of value 488 at various tilt angleswith respect to an axis 490. As shown in those figures, the section ofthe security feature 482 that a viewer sees as a synthetic image aslight from a light source 492 is reflected from the security feature 482may move as indicated by the lighter or brighter band and the arrow 494.According to examples, the magnetically-orientable flakes in thesecurity feature 482 may include various colors and/or color-shiftingpigment such that the color of the synthetic image may vary as thearticle of value 488 is tilted, e.g., the magnetically-orientable flakesmay have a gold-to-green pigment.

Turning now to FIG. 4N, there is shown an example of the mask 480 inwhich openings or cutouts in the mask 480 have different widths. Theuneven widths of the steps in the mask 480 may result in a zoomingeffect, in which the portions of the article 482 that are locatedunderneath the steps having the larger widths have a larger appearanceas compared to the portions of the article 482 that are locatedunderneath the steps having the smaller widths. In the example shown inFIG. 4N, the characters “2”, “5”, “7”, “A”, and “3” may be printed ontothe substrate 116 with the fluid carrier 118. That is, a Guilloche orother graphic art may be provided on the substrate 116 and the fluidcarrier 118, which may be a magnetic ink, may be applied or printed intothe characters shown in FIG. 4N. The article 482 may be provided as asecurity element on an article of value 488 as shown in FIG. 4O. Asshown in that figure, under a normal viewing angle, the numeral “3” mayappear the brightest or may otherwise be the most prominent syntheticimage.

The synthetic kinematic image generated by the security element 482 isfurther described with respect to FIGS. 4P and 4Q, which depict thearticle of value 488 at various tilt angles with respect to an axis 490.As shown in those figures, the section of the security feature 482 thata viewer sees as a synthetic image as light from a light source 492 isreflected from the security feature 482 may move as indicated by thelighter or brighter band and the arrow 494. Thus, for instance, in FIG.4P, the numeral “7” may have the most prominent appearance among thecharacters in the security element 482. Additionally, as the article ofvalue 488 is tilted further as shown in FIG. 4Q, the numeral “2” mayhave the most prominent appearance among the characters in the securityelement 482. According to examples, the magnetically-orientable flakesin the security feature 482 may include various colors and/orcolor-shifting pigment such that the color of the synthetic image mayvary as the article of value 488 is tilted, e.g., themagnetically-orientable flakes may have a gold-to-green pigment.

Turning now to FIG. 5A, there is shown a top view of an apparatus 500for orienting magnetically-orientable flakes according to anotherexample of the present disclosure. The apparatus 500 depicted in FIG. 5Aincludes many of the same features as those described above with respectto FIG. 2B and thus, those common features will not be described indetail with respect to FIG. 5A. However, the apparatus 500 depicted inFIG. 5A differs from the apparatus 200 depicted in FIG. 2B in that themask 502 in the apparatus 500 has a wedge-shaped opening 504. As thewedge-shaped opening 504 will result in the application of energy fromthe radiation source 120 on different portions of the fluid carrier 118as the substrate 116 moves in the feed direction 114, themagnetically-orientable flakes or particles in the region 506 resultingfrom the application of the magnetic field may have orientations anddihedral angle values that differ along a gradient as shown in FIG. 5A.That is, different portions of the fluid carrier 118 may be under theinfluence of different vector forces 202 (FIG. 2A) and thus may havedifferent orientations and dihedral angle values when radiation isapplied onto the fluid carrier 118 through the wedge-shaped opening 504.

The magnetically-orientable flakes in the regions 508 and 510 may nothave been exposed to the same inclining and declining portions of themagnetic field lines 202 in the process of solidifying the region 506.Instead, the magnetically-orientable flakes in the regions 508 and 510may be aligned in the direction of different—perhaps declining portionsof the magnetic lines 202. That is, the regions 508 and 510 may beexposed to radiation from the radiation source 120 when the regions 508and 510 come out from under the mask 502 and may thus at least begin tosolidify, e.g., become cured, at least partially fixing themagnetically-orientable flakes in their instant orientations. While theregions 508 and 510 begin to solidify, the magnetically-orientableflakes in those regions may be aligned with the declining portion 224 ofthe magnetic field lines 202. As a result, the magnetically-orientableflakes in the regions 508 and 510 may have orientations and dihedralangle values that are different as compared with the orientations anddihedral angle values of the magnetically-orientable flakes in theregion 506.

According to examples, the use of the wedge-shaped opening 504 in themask 502 may result in the magnetically-orientable flakes in the region506 having a helical arrangement with respect to each other along thedirection perpendicular or transverse to the feed direction 114 andwithin the plane of substrate 116. A simplified example of themagnetically-orientable flakes in the region 506 arranged in a gradientis depicted in FIG. 5B. FIG. 5B, particularly, depicts a simplifiedisometric view 520 of the magnetically-orientable flakes contained inthe region 506 of the fluid carrier 118 depicted in FIG. 5A. In otherexamples, a similar effect may be obtained through use of a mask inwhich the angled section has a stepped configuration.

In FIG. 5B, the magnetically-orientable flakes 522 are depicted as beingarranged in the fluid carrier 118 along longitudinal rows of an array ofmagnetically-orientable flakes 522 in the region 506. As shown, all ofthe magnetically-orientable flakes 522 in each of the rows “a-g” may beoriented at the same dihedral angle with respect to the major plane ofthe substrate 116. That is, all of the magnetically-orientable flakes522 in row “a” may be oriented at the same angle α_(a) with respect tothe major plane of the substrate 116 and the direction of substratemotion 114, in which the angle α_(a) is between about 90°<α_(a)<180°.Likewise, the magnetically-orientable flakes 522 in row “b” may beoriented at the same angle α_(b) with respect to the major plane of thesubstrate 116 and the direction of substrate motion 114, in which theangle α_(b) differs from the angle α_(a). The angle of tilt of themagnetically-orientable flakes 522 in the remaining rows c-g may alsodiffer from the tilt angles of the magnetically-orientable flakes 522 inthe other rows.

In FIG. 5B, the magnetically-orientable flakes 522 are also depicted asbeing arranged in the fluid carrier 118 along transverse columns of anarray in the region 506. The values of the tilt angles of themagnetically-orientable flakes 522 along each of the transverse columns“A”-“H” vary in a step-wise fashion. For instance, the values of thetilt angles in the transverse columns “A”-“H” change from the value ofangle δ₁ (shown in FIG. 5B as being in the range 180°>δ₁>90°) to theangle δ_(n) (shown in FIG. 5B as being in the range 90°>δ_(n)>0°). As aresult of this variation in the value of tilt angles along a string ofmagnetically-orientable flakes 522 in a single transverse column “A”,the magnetically-orientable flakes 522 may form a helical orientationalong the direction orthogonal to the direction of motion and lyingwithin the plane of the substrate 116.

The shifting optical effects of the magnetically-orientable flakes 522in the region 506 are further shown and described with respect to FIGS.5C-5F. Each of FIGS. 5C-5F shows an example of an optical element 530 atdifferent tilt angles. The optical element 530 may be an opticalsecurity device, which may be provided on a banknote, stock certificate,or the like. FIG. 5C depicts the optical characteristics of the opticalelement 530 when the optical element 530 is viewed at a first angle,e.g., from a direction close to normal to the optical element 530. Thegraph 532 shows that the left side of the optical element 530 appearsblack (e.g., dark), that the right side of the optical element 530appears white (e.g., bright), and that the optical element 530 graduallychanges from black to white from the left side to the right side of theoptical element 530.

FIG. 5D depicts an example of the optical characteristics of the opticalelement 530 when the optical element 530 is tilted away from an observeras noted by the arrow 534. For instance, the top of the optical element530 may be tilted about 15°-25° away from the observer. The graph 536shows that both the left side of the optical element 530 and the rightside of the optical element 530 appear black (e.g., dark) and that thecenter of the optical element 530 appears white (e.g., bright). Asshown, as the top portion of the optical element 530 is tilted away froman observer, a bright band may appear to move from the right side of theoptical element 530 to the left side of the optical element 530. Inother words, the magnetically-orientable flakes 522 in the opticalelement 530 may be oriented such that tilting of the optical element 530in one direction (e.g., top to bottom) results in an optical shift inthe opposite direction (e.g., right to left).

FIG. 5E depicts an example of the optical characteristics of the opticalelement 530 when the top portion of the optical element 530 is tiltedfurther away from the observer. For instance, the top of the opticalelement 530 may be tilted to an angle greater than about 25° away fromthe observer as shown by the arrow 538. The graph 540 shows that theleft side of the optical element 530 appears white (e.g., bright) andthat the remainder of the optical element 530 appears black (e.g.,dark). As shown, as the top portion of the optical element 530 isfurther tilted away from an observer, the bright band may appear to moveto the left side of the optical element 530.

FIG. 5F depicts an example of the optical characteristics of the opticalelement 530 when the optical element 530 is flexed diagonally as notedby the arrow 542. As shown, a Z-shaped white band may be visible as theoptical element 530 is flexed diagonally. The graph 544 shows thevisible Z-shaped band graphically.

Although the optical element 530 has been depicted as having a squareshape, it should be understood that the optical element 530 may have anyshape.

Turning now to FIG. 6A, there is shown a top view of an apparatus 600for orienting magnetically-orientable flakes according to anotherexample of the present disclosure. The apparatus 600 depicted in FIG. 6Aincludes many of the same features as those described above with respectto FIG. 5A and thus, those common features will not be described indetail with respect to FIG. 6A. However, the apparatus 600 depicted inFIG. 6A differs from the apparatus 500 depicted in FIG. 5A in that thewedge-shaped (or triangular-shaped) opening 604 in the mask 602 containstwo sides of an isosceles or equilateral triangle. As thetriangular-shaped opening 604 will result in the application ofradiation from the radiation source 120 on different portions of thefluid carrier 118 as compared with the wedge-shaped opening 504, themagnetically-orientable flakes or particles in the region 606 resultingfrom the application of the magnetic field may have orientations thatdiffer along a gradient as shown in FIG. 6A. That is, different portionsof the fluid carrier 118 may be under the influence of different vectorforces (shown schematically as magnetic field lines 202) (FIG. 2A) andthus may have different orientations when energy is applied onto thefluid carrier 118 through the opening 604.

The magnetically-orientable flakes in the regions 608 and 610 may nothave been exposed to the same inclining and declining portions of themagnetic field lines 202 in the process of solidifying the region 606.Instead, the magnetically-orientable flakes in the regions 608 and 610may be aligned in the direction of different—perhaps declining portionsof the magnetic lines 202. That is, the regions 608 and 610 may beexposed to radiation from the radiation source 120 when the regions 608and 610 come out from under the mask 602 and may thus at least begin tosolidify, e.g., become cured, at least partially fixing themagnetically-orientable flakes in their instant orientations. While theregions 608 and 610 at least partially solidify, themagnetically-orientable flakes in those regions may be aligned with thedeclining portion 224 of the magnetic field lines 202. As a result, themagnetically-orientable flakes in the regions 608 and 610 may haveorientations and dihedral angle values that are different as comparedwith the orientations and dihedral angle values of themagnetically-orientable flakes in the region 606.

According to examples, the use of the wedge-shaped opening 604 in themask 602 may result in the magnetically-orientable flakes in the region606 having a bi-helical arrangement with respect to each other along thedirection perpendicular to the feed direction 114 and within the planeof substrate 116. A simplified example of the magnetically-orientableflakes in the region 606 arranged in a gradient is depicted in FIG. 6B.FIG. 6B, particularly, depicts a simplified isometric view 620 of themagnetically-orientable flakes contained in the region 606 depicted inFIG. 6A. In other examples, a similar effect may be obtained through useof a mask in which the angled sections each has a stepped configuration.

In FIG. 6B, the magnetically-orientable flakes 622 are depicted as beingarranged along longitudinal rows of an array of magnetically-orientableflakes 622 in the region 606, which is depicted as be composed of twosections 624 and 626. Each of the sections 624 and 626 is depicted asbeing arranged on opposite sides of a center line 628 that coincideswith the tip of the triangular-shaped opening 604. As shown, each of thesubset of magnetically-orientable flakes 622 in adjacent,longitudinally-extending rows may be oriented at the same dihedral anglewith respect to the major plane of the substrate 116. That is, all ofthe magnetically-orientable flakes 622 in one of the rows in the firstsection 624 may be oriented at the same angle α with respect to themajor plane of the substrate 116 and the direction of substrate motion114, in which the angle α is between about 0°<α<180°. Likewise, themagnetically-orientable flakes 622 in a second row of the first section624 may be oriented at the same angle α′ with respect to the major planeof the substrate 116 and the direction of substrate motion 114, in whichthe angle α′ differs from the angle α. The dihedral angle of themagnetically-orientable flakes 622 in the remaining longitudinallyextending rows may also differ from the dihedral angles of themagnetically-orientable flakes 622 in the other rows.

In FIG. 6B, the magnetically-orientable flakes 622 are also depicted asbeing arranged in the fluid carrier along transverse columns of an arrayin the region 606. The values of the dihedral angles of themagnetically-orientable flakes 622 along each of the transverse columnsin the first section 624 vary in a step-wise fashion. For instance, thevalues of the tilt angles in the transverse columns change from thevalue of angle δ₁ (shown in FIG. 6B as being in the range 0°<δ₁<180°) tothe angle δ_(n). As a result of this variation in the value of dihedralangles along a string of magnetically-orientable flakes 622 in a singletransverse column of the first section 624, the magnetically-orientableflakes 622 in the first section 624 may form a helical orientation. Themagnetically-orientable flakes 622 in the transverse columns of thesecond section 626 may be arranged and oriented to have a differenthelical orientation. The magnetically-orientable flakes 622 in the twosections 624 and 626 may be arranged and oriented in a mirror copyconfiguration to provide a clockwise helical configuration to themagnetically-orientable flakes in second section 626 and to provide acounter-clockwise helical configuration to the magnetically-orientableflakes in first section 624. As such, the magnetically-orientable flakesin each of the transverse columns of magnetically-orientable flakes 622in the region 606 may have bi-helical orientations as shown in FIG. 6B.The shifting optical effects of the magnetically-orientable flakes 622in the region 606 are further shown and described with respect to FIGS.6C-6E. Each of FIGS. 6C-6E shows an example of an optical element 630 atdifferent tilt angles. The optical element 630 may be an opticalsecurity device, which may be provided on a banknote, stock certificate,or the like. FIG. 6C depicts the optical characteristics of the opticalelement 630 when the optical element 630 is viewed at a first angle,e.g., from a direction normal or close to normal to the optical element630. The graph 632 shows that the center of the optical element 630appears white (e.g., bright) and that the optical element 630 graduallygets more black (e.g., darker) closer to the left and right sides of theoptical element 630.

FIG. 6D depicts an example of the optical characteristics of the opticalelement 630 when the top portion of the optical element 630 is tiltedaway from an observer as noted by the arrow 634. For instance, the topof the optical element 630 may be tilted about 15° away from theobserver. The depiction of the optical element 630 shows that the widebright band shown in FIG. 6C may be split into two bright bands ofsmaller widths that simultaneously move to the left and right edges ofthe optical element 630. The graph 636 shows that tilting of the opticalelement 630 may result in two white peaks. In other words, themagnetically-orientable flakes 622 in the optical element 630 may beoriented such that tilting of the optical element 530 in one direction(e.g., top to bottom) results in multiple optical shifts in the oppositedirection (e.g., left to right and right to left).

FIG. 6E depicts an example of the optical characteristics of the opticalelement 630 when the top portion of the optical element 630 is tiltedfurther away from the observer. For instance, the top of the opticalelement 630 may be tilted to an angle greater than about 15° away fromthe observer as shown by the arrow 638. As shown, the further tiltingmay cause the white bands to get closer to the left and right edges andto become narrower. In addition, the darker zone near the center of theoptical element 630 may become wider. The graph 640 shows that the whitepeaks are closer to the edges and have become narrower while the darkerzone in the middle has increased in width.

Although the optical element 630 has been depicted as having a squareshape, it should be understood that the optical element 630 may have anyshape.

With reference now to FIGS. 7-10, there are respectively shown flowdiagrams of methods 700-1000 for orienting magnetically-orientableflakes, according to an example of the present disclosure. The methods700-1000 are described with respect to the apparatuses 100, 200, 500,and 600 discussed above. It should, however, be understood that themethods 700-1000 may be implemented by apparatuses having otherconfigurations than those configurations of the apparatuses 100, 200,500, and 600. Each of methods 700-1000 is merely exemplary. Methods700-1000 may include greater or lesser steps. The steps of methods700-1000 may be performed in any order.

With reference first to FIG. 7, at block 702, a fluid carrier 118containing magnetically-orientable flakes may optionally be applied ontoa substrate 116. Application of the fluid carrier 118 may be optional ininstances in which the fluid carrier 118 has previously been appliedonto the substrate 116.

At block 704, the substrate 116 and the fluid carrier 118 may be movedthrough a magnetic field. As described herein, the magnetic field mayinfluence the magnetically-orientable flakes in the fluid carrier 118 tobe respectively oriented in one of multiple orientations. The multipleorientations may be dihedral angles with respect to the plane of thesubstrate 116. According to examples, the magnetic field has a strengthof at least 0.0001 tesla.

At block 706, during movement of the substrate 116 through the magneticfield, radiation may be applied onto a plurality of selected portions ofthe fluid carrier 118 through at least one opening 124 in a mask 122 tocure the fluid carrier 118 at the plurality of selected portions and fixthe magnetically-orientable flakes in the plurality of selected portionsat the respective angular orientations as influenced by the magneticfield. According to examples, radiation may be applied to cause themagnetically-orientable flakes in a first selected portion to be fixedat a first orientation and the magnetically-orientable flakes in asecond selected portion to be fixed at a second orientation, in whichthe first orientation differs from the second orientation. Radiation mayalso be applied to cause the magnetically-orientable flakes in a thirdselected portion to be fixed at a third orientation, in which the thirdorientation differs from the first orientation and the secondorientation.

As discussed herein, the substrate 116 may be moved along a feeddirection 114 through the magnetic field and radiation may be applied tofix the magnetically-orientable flakes in the plurality of selectedportions at respective orientation angles that are different from theorientation angle of magnetically-orientable flakes in other portionsand are also different from the intersecting angles with respect to aplane that extends along the feed direction 114 and is tangent to thesubstrate 116 surface. In addition, radiation may be applied onto theplurality of selected portions when the magnetically-orientable flakesin the plurality of selected portions are substantially aligned withrespective vector forces of the magnetic field. Moreover, the magneticfield may be generated by at least one stationary magnet 102 and thesubstrate 116 may be moved between the mask 122 and the magnet 102. Inone example, the substrate 116 may be moved at a speed of at least about0.3 meters/min (1 ft/min). In other examples, the substrate 116 may bemoved at a speed from about 1.5 meters/min (5 ft/min) to about 180meters/min (600 ft/min).

Turning now to FIG. 8, at block 802, a substrate 116 may be moved in afirst direction 114 through a magnetic field and a radiation footprintproviding radiation. The magnetic field may have a strength of at least0.0001 tesla. The ink (e.g., fluid carrier 118) withmagnetically-orientable flakes is disposed on the substrate 116 and theradiation footprint has a leading edge. The magnetic field may also begenerated by at least one magnet 102 and the radiation footprint may bestationary relative to the at least one magnet 102.

At block 804, during movement of the substrate 116 through the magneticfield, radiation may be applied to a portion of the substrate 116 whenthe portion of the substrate 116 is in an extent of the leading edgealong the first direction 114. As discussed above, the leading edge ofthe radiation footprint may vary in the feed direction 114 and may beprovided through an opening 124 in a mask 122. Additionally, the leadingedge may have a continuous edge having at least a 2 mm extent in thefirst direction and at least a 2 mm extent in a direction normal to thefirst direction and parallel to the plane of the substrate 116.

With reference now to FIG. 9, at block 902, a substrate 116 with a fluidcarrier deposited thereon may be moved relative to an external magneticinduction and a radiation footprint to provide curing radiation. Thefluid carrier may include magnetically-orientable flakes and theradiation footprint may have a leading edge with non-zero extent in thedirection of substrate motion.

At block 904, the fluid carrier may be cured with the curing radiationas the fluid carrier is moving in the radiation footprint. The fluidcarrier may be partially or completely cured while moving in theradiation footprint. In some examples, the leading edge of the radiationfootprint may be the points on the substrate that are first exposed tothe curing radiation as the substrate moves in the feed direction. Insome examples, the fluid carrier begins to cure as the fluid carrierpasses the leading edge. In addition, for at least part of the leadingedge, the external magnetic induction has an orthogonal projection ontoa plane and contains a substrate velocity vector, in which the plane isnormal to the substrate 116. The orthogonal projection may vary indirection by at least 0.01 radians and may have a strength of at least0.0001 tesla. The orthogonal projection may vary in direction by atleast 0.05 radians. According to examples, the leading edge has anextent in the direction of substrate motion of at least 2 mm and mayhave a continuous edge. The continuous edge may also have at least a 2mm extent along the substrate 116 in a direction normal to the directionof substrate motion. In addition, or alternatively, the radiationfootprint may be stationary relative to the external magnetic induction.

Turning now to FIG. 10, at block 1002, a substrate 116 with fluidcarrier 118 deposited thereon may be moved relative to an externalmagnetic induction and a radiation footprint to provide curingradiation. The fluid carrier 118 (or ink) may includemagnetically-orientable flakes and the radiation footprint may have aleading edge with non-zero extent in the direction of substrate motion.For instance, the leading edge may include a continuous edge having anextent in the direction of substrate motion of at least 2 mm. Thecontinuous edge may additionally or alternatively have at least a 2 mmextent along the substrate in a direction normal to the direction ofsubstrate motion.

At block 1004, the magnetically-orientable flakes may be oriented by theexternal magnetic induction, in which the value of the dihedral angle oforientation may vary by at least 0.01 radians along at least part of theleading edge.

At block 1006, the fluid carrier 118 may be cured with the curingradiation as the fluid carrier 118 is moving in the radiation footprint.The fluid carrier 118 may first be exposed to the curing radiation atthe radiation footprint. In some examples, the fluid carrier 118 beginsto cure as the fluid carrier passes the leading edge. According toexamples, the radiation footprint may be stationary relative to theexternal magnetic induction and may be provided through illumination ofan opening 124 in a mask 122 with a radiation source 120. In addition,or alternatively, the orthogonal projection of the external magneticinduction may have a strength of at least 0.001 tesla and the magneticinduction may vary in direction by at least 0.05 radians.

According to examples, any or all of the methods 700-1000 disclosedherein may be performed at multiple stations of an apparatus 100 suchthat articles may be fabricated to include multiple layers of fluidcarriers as discussed above.

Although described specifically throughout the entirety of the instantdisclosure, representative examples of the present disclosure haveutility over a wide range of applications, and the above discussion isnot intended and should not be construed to be limiting, but is offeredas an illustrative discussion of aspects of the disclosure.

What has been described and illustrated herein is an example of thedisclosure along with some of its variations. The terms, descriptionsand figures used herein are set forth by way of illustration only andare not meant as limitations. Many variations are possible within thespirit and scope of the disclosure, which is intended to be defined bythe following claims—and their equivalents—in which all terms are meantin their broadest reasonable sense unless otherwise indicated.

What is claimed is:
 1. A method comprising: moving a substrate, along afeed direction, through a magnetic field, wherein the substrate includesa fluid carrier containing magnetically-orientable flakes, wherein themagnetic field orients the magnetically-orientable flakes in one ofmultiple orientations; and during movement of the substrate through themagnetic field, applying radiation onto a plurality of selected portionsof the fluid carrier through two or more openings in a mask, wherein themask is positioned between the substrate and a radiation source, and thetwo or more openings in the mask are positioned on opposite sides of anundulation point of the magnetic field; wherein the flakes are orientedin a helical or bi-helical arrangement with respect to each other alonga direction that is perpendicular to the feed direction.
 2. The methodaccording to claim 1, wherein the plurality of selected portionsincludes a first selected portion and a second selected portion andwherein applying radiation onto a plurality of selected portions of thefluid carrier further comprises applying radiation to cause themagnetically-orientable flakes in the first selected portion to be fixedat a first orientation and the magnetically-orientable flakes in thesecond selected portion to be fixed at a second orientation, wherein thefirst orientation differs from the second orientation.
 3. The methodaccording to claim 1, wherein applying radiation further comprisesapplying radiation to fix the magnetically-orientable flakes in theplurality of selected portions at respective orientation angles that aredifferent from the orientation angle of magnetically-orientable flakesin other portions and are also different from the intersecting angleswith respect to a plane that extends along the feed direction and istangent to the substrate surface.
 4. The method according to claim 1,wherein the magnetic field influences the magnetically-orientable flakesto be substantially aligned with the magnetic field and wherein applyingradiation onto the plurality of selected portions further comprisesapplying radiation onto the plurality of selected portions when themagnetically-orientable flakes in the plurality of selected portions aresubstantially aligned with respective vector forces of the magneticfield.
 5. The method according to claim 1, wherein moving the substratefurther comprises moving the substrate at a speed of at least about 0.3meters/min (1 ft/min).
 6. The method according to claim 1, whereinmoving the substrate further comprises moving the substrate at a speedfrom about 1.5 meters/min (5 ft/min) to about 180 meters/min (600ft/min).
 7. The method according to claim 1, further comprising:applying the fluid carrier containing the magnetically-orientable flakesonto the substrate prior to moving the substrate through the magneticfield.
 8. The method according to claim 1, wherein the magnetic fieldhas a strength of at least 0.001 tesla.
 9. The method according to claim1, wherein the applied radiation is generated by at least one radiationsource and the mask blocks a portion of the radiation generated by theat least one radiation source to cause the magnetically-orientableflakes in different locations of the fluid carrier to be respectivelyoriented in a manner that cause the magnetically-orientable flakes todisplay an ortho-parallactic effect as the substrate is tilted.
 10. Themethod according to claim 1, wherein the applied radiation is generatedby at least one radiation source and the mask blocks a portion of theradiation generated by the at least one radiation source to cause themagnetically-orientable flakes in different locations of the fluidcarrier to have one of different sizes to cause themagnetically-orientable flakes to display synthetic images of multiplesizes.
 11. The method according to claim 10, further comprising:printing characters on the substrate, wherein the characters arepositioned to be aligned with the magnetically-orientable flakes havingrespective ones of the multiple sizes.
 12. A method comprising: moving asubstrate in a first direction through a magnetic field having astrength of at least 0.001 tesla, wherein ink withmagnetically-orientable flakes is disposed on the substrate; and duringmovement of the substrate through the magnetic field, providingradiation through at least one opening in a mask, wherein the at leastone opening has at least one open side; wherein the at least one openingin the mask defines a radiation footprint with a leading edge; curingthe magnetically-orientable flakes, when a portion of the substratemoves past the leading edge, in a helical or hi-helical arrangement withrespect to each other along a direction that is perpendicular the firstdirection.
 13. The method as set forth in claim 12, wherein the leadingedge varies in shape in the first direction.
 14. The method as set forthin claim 12, wherein the magnetic field is generated by at least onemagnet and the radiation is stationary relative to the at least onemagnet.
 15. The method as set forth in claim 12, wherein the leadingedge comprises a continuous edge having at least a 2 mm extent in thefirst direction and wherein the continuous edge has at least a 2 mmextent in a direction normal to the first direction.
 16. A methodcomprising: moving a substrate with a fluid carrier deposited thereonrelative to an external magnetic induction and a radiation footprintfrom a mask with at least one opening, the fluid carrier comprisingmagnetically-orientable flakes, the radiation footprint having a leadingedge with non-zero extent in a feed direction; and curing themagnetically-oriented flakes in a helical or bi-helical arrangement withrespect to each other along a direction that is perpendicular to theteed direction; wherein a first region of the magnetically-orientableflakes has a dihedral angle α with respect to a major plane of thesubstrate, wherein α is in a range of about 0°<β<90° taken in the feeddirection; wherein a second region of the magnetically-orientable flakeshas a dihedral angle α with respect to the major plane of the substrate,wherein β is in a range of about 0°<β<90° in a direction opposite theteed direction.
 17. The method as set forth in claim 16, wherein theleading edge has an extent in the feed direction of at least 2 mm. 18.The method as set forth in claim 16, wherein the radiation footprint isstationary relative to the external magnetic induction.
 19. The methodas set forth in claim 16, wherein the mask blocks a portion of radiationthereby causing the magnetically-orientable flakes in the first regionand the second region to be respectively oriented in a manner thatcauses an ortho-parallactic effect as the substrate is tilted.
 20. Themethod according to claim 16, Wherein moving the substrate furthercomprises moving the substrate at a speed of at least about 0.3meters/rain (1 ft/min).